memory: allow memory_region_register_iommu_notifier() to fail

Currently, when a notifier is attempted to be registered and its
flags are not supported (especially the MAP one) by the IOMMU MR,
we generally abruptly exit in the IOMMU code. The failure could be
handled more nicely in the caller and especially in the VFIO code.

So let's allow memory_region_register_iommu_notifier() to fail as
well as notify_flag_changed() callback.

All sites implementing the callback are updated. This patch does
not yet remove the exit(1) in the amd_iommu code.

in SMMUv3 we turn the warning message into an error message saying
that the assigned device would not work properly.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 10 insertions, 8 deletions

diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
index db051dcac8..e2fbb8357e 100644
--- a/hw/arm/smmuv3.c
+++ b/hw/arm/smmuv3.c
@@ -1469,20 +1469,21 @@ static void smmuv3_class_init(ObjectClass *klass, void *data)
     dc->realize = smmu_realize;
 }
 
-static void smmuv3_notify_flag_changed(IOMMUMemoryRegion *iommu,
-                                       IOMMUNotifierFlag old,
-                                       IOMMUNotifierFlag new)
+static int smmuv3_notify_flag_changed(IOMMUMemoryRegion *iommu,
+                                      IOMMUNotifierFlag old,
+                                      IOMMUNotifierFlag new,
+                                      Error **errp)
 {
     SMMUDevice *sdev = container_of(iommu, SMMUDevice, iommu);
     SMMUv3State *s3 = sdev->smmu;
     SMMUState *s = &(s3->smmu_state);
 
     if (new & IOMMU_NOTIFIER_MAP) {
-        int bus_num = pci_bus_num(sdev->bus);
-        PCIDevice *pcidev = pci_find_device(sdev->bus, bus_num, sdev->devfn);
-
-        warn_report("SMMUv3 does not support notification on MAP: "
-                     "device %s will not function properly", pcidev->name);
+        error_setg(errp,
+                   "device %02x.%02x.%x requires iommu MAP notifier which is "
+                   "not currently supported", pci_bus_num(sdev->bus),
+                   PCI_SLOT(sdev->devfn), PCI_FUNC(sdev->devfn));
+        return -EINVAL;
     }
 
     if (old == IOMMU_NOTIFIER_NONE) {
@@ -1492,6 +1493,7 @@ static void smmuv3_notify_flag_changed(IOMMUMemoryRegion *iommu,
         trace_smmuv3_notify_flag_del(iommu->parent_obj.name);
         QLIST_REMOVE(sdev, next);
     }
+    return 0;
 }
 
 static void smmuv3_iommu_memory_region_class_init(ObjectClass *klass,